1. Field of the Invention
The present invention relates to a cell control system, and particularly relates to a cell control system that estimates an influence of noise in a plurality of machines.
2. Description of the Related Art
FIG. 7 is a diagram illustrating a cell control system (manufacturing control system) that manages a manufacturing cell including a plurality of manufacturing machines. The cell control system improves an operation rate of the whole manufacturing cell by instructing each manufacturing cell to operate based on a manufacturing plan indicated by a production planning device while managing usage states of the manufacturing machines or determining a manufacturing machine to be used.
At the time of operating a manufacturing cell according to the manufacturing plan, when an alarm occurs in a manufacturing machine included in the operated manufacturing cell to suspend an operation, productivity in the manufacturing cell decreases. As a result, an operation rate of the whole manufacturing cell decreases.
As a conventional technology for responding to the occurrence of the alarm in the manufacturing machine, for example, Japanese Patent Application Laid-Open No. 2011-243118 discloses a monitoring diagnostic device that uses a plurality of parts in a monitoring target device as an object to be monitored, collects time series physical quantities of an attached sensor, detects a defect, diagnoses a cause thereof, and determines presence/absence of a causal relationship from a correlation coefficient between sensor data items. In addition, Japanese Patent Application Laid-Open No. 8-320726 discloses a diagnosis/analysis device that interprets a correlated pair of signals fetched from a plurality of objects to be controlled, analyzes presence/absence of a defect through comparison with correlation information at normal time, and outputs a conclusion of a fault location from presence/absence information of the defect.
In general, measures are taken against noise (electrical disturbance or physical vibration) in the manufacturing machine to prevent the occurrence of the alarm. Such measures are carried out in the following procedure.
Procedure a1) A state of noise of each machine is measured.
Procedure a2) A probability that an alarm will occur is analyzed from a result of measurement in procedure a1.
Procedure a3) A cause of the alarm is specified from an analysis result, and measures against the noise is taken to prevent the cause.
However, in an environment such as a factory in which a plurality of manufacturing machines continue to operate, an influence of noise changes in association with a combination of a plurality of conditions such as arrangement or wiring of the manufacturing machines, an operation pattern, etc. Thus, in many cases, it is difficult to specify the cause of the alarm even when the above procedures are performed. In such a state, both the noise and an operating condition need to be simultaneously analyzed. However, in practice, since the plurality of manufacturing machines simultaneously operates, the operation pattern as a whole is complex, and analysis of the cause is difficult.
On the other hand, in the technology disclosed in Japanese Patent Application Laid-Open No. 2011-243118, since diagnosis is performed using only one sensor in the device, it is not effective to apply the technology to a manufacturing cell in which a plurality of machines simultaneously operates. In addition, in the technology disclosed in Japanese Patent Application Laid-Open No. 8-320726, even though a defect may be diagnosed in a machine system including a plurality of control devices, a cause of the defect may be estimated only in a state in which the defect is registered in a database in advance.